That is actually a very common misconception. There are many therapies today which are now commonly used in mainstream medicine which were previously alternative therapies.
Many supplements have been shown to "not" be effective, but when manufacturer comparisons were done on products that showed promise (Fish Oil was an example), it was demonstrated that some altnerative therapies or supplements actually were useful in treating some conditions, but it depended heavily on how the product was processed, stored, quality of initial goods, and so forth.
At any rate, when people run out of options and still aren't recovering and have tried everything else, they'll inevitably be forced to try therapies that are more fringe, and that is unfortunate, but unlikely to ever stop. Fortunately experimental clinical testing continues to pave the way for further studies.